tools: align parallel execution with runtime limits

pkg/tools/web.go

@@ -12,7 +12,6 @@ import (
 	"time"
 
 	"clawgo/pkg/logger"
-	
 )
 
 const (
@@ -144,6 +143,10 @@ type WebFetchTool struct {
 	maxChars int
 }
 
+func (t *WebFetchTool) ParallelSafe() bool {
+	return true
+}
+
 func NewWebFetchTool(maxChars int) *WebFetchTool {
 	if maxChars <= 0 {
 		maxChars = 50000